1. Take aways all guns in the beginning
2. Make days shorter
3. At the end of each day, give access to shop
4. Let us purchase guns at shop
5. Let us purchase upgrades on guns or character. Examples: Reload Speed, Accuracy, Damage etc.
6. Purchasable Castle upgrades with visual feedback(buy a moat, a moat appears).
Good unique graphics, but there needs to be a sense of progression. People don't play to get high scores unless the base game is worth it. Good luck.
Thank you!